Question

Emerson effect indicates the existence of
a. Two pigment systems
b. Two photosynthetic units
c. Two photophosphorylation
d. None of the above

Answer 1

Emerson effect was given by Robert Emerson, where he observed in plants, that rate of photosynthesis increases if the chloroplast of the plants is exposed to the light of wavelength 680nm or more than 680nm.

Complete answer:
- When Emerson exposed the green plants to the light that is greater than 680 nm, the rate of photosynthesis is decreased, in fact, it Is the wavelength of the length where the maximum is absorbed by the chloroplast.
- When Emerson exposed plants to the light of wavelength less than 680nm, in this wavelength also the rate of photosynthesis was decreased.
- But when he repeated the experiment by exposing the plant to both of the wavelengths at a time, which abruptly increases the photosynthesis, to the high rate, from this experiment he understood that plant has two different photosystems or pigment systems, such as PSI and PSII where one system is for higher wavelengths and one is for lower wavelengths, but if both are exposed at a time it peaks the rate of photosynthesis.
- As Robert Emerson observed this, hence this is called the Emerson effect.
- In this when wavelengths are exposed simultaneously, the rate of photosynthesis is higher than the sum of the right light and far-red light wavelengths.
- So Emerson effect tells about the presence of two different photosystems in the chloroplast.

Hence, the correct answer is option (A).

Note: Chlorophylls in the plants when exposed to light, activates and excites the reaction center, which causes an increase in energy, and this energy is carried by electrons carriers and transfer to photosystems to produce energy-carrying organic molecules.